The invention relates to a crank press having a lateral rod ejector. The arrangement of the invention includes a reciprocating sled actuated by a crank drive, the side facing the die having a rod holder, a press ram and a reciprocating ejector rod reciprocably mounted in the press ram. The ejector rod is actuated by an angle or toggle lever which is entrained by the sled movement, said toggle lever being in continuous contact with a control cam via a roller, the motion of which being provided by a gear wheel mounted on the crank shaft.
There is already known and disclosed in German Pat. No. 1,750,033 an arrangement in a crank press for transferring the rotary movement of the main crank drive coacting with the drive of a reciprocating sled and having a stationarily mounted auxiliary crank drive having the same crank radius and an identical crank rod length as the main crank drive. The auxiliary crank drive is arranged parallel to the main crank drive and is coupled to it via a gear wheel chain and via a swing frame pivotally mounted about the control shaft. The control cam coacts with a toggle lever which furnishes a stroke limit for the ejector. The entire known arrangement serves the purpose to attain by means of a coincidence of the angular velocity of the main and auxiliary crank drive a predetermined reciprocating motion and stroke sequence of the ejector.
The drawbacks of this known driving arrangement for a crank press are easily recognizable:
First of all, the construction of the auxiliary crank is expensive; secondly, a swing frame mounted on the control shaft is required in which all of the gear wheels coacting with the sled are mounted. Consequently, the gear wheels, which are continuously engaging each other, undergo the swing movement of the swing frame in conformance with the movement of the auxiliary crank shaft drive which causes at least a certain additional motion in the machine due to vibration.